I recently had my pool pump motor fail. It's a 230 V single phase capacitor start motor on a Hayward Superpump II. I went to start it one day and it wouldn't turn, but would just hum. I couldn't find any faults with the centrifugal switch or the supply voltage, and the rotor turned freely by hand, so I changed the start capacitor. Changing the start capacitor made the motor turn briefly, then it returned to humming and then began to smoke. I don't know the exact age of the motor, but it probably has several years on it. I figured that its time had come and bought a new motor from the local pool store.
The new pump was a knock off, a 1.5 hp labeled White River. The sticker on it indicated that it came wired from the factory for 230 V operation, and I double checked per the schematic on the housing. I'm fairly certain that I wired it correctly. Ground to the ground screw, one leg to the line 1 terminal, and the other leg to the line 2 terminal. Upon energizing the motor, it turned very slowly and noisily and then tripped the breaker, within 3 seconds or so. I checked the rotor and found that it turned freely, so I reset the breaker and tried again. Once again, it turned slowly and noisily and tripped the breaker, this time with accompanying smoke, and again within 3 seconds or so.
I removed the pump and checked my supply voltage again. I checked both legs and the total voltage both before and after the breaker, both with the breaker on and off. I found everything to be correct, for no load at least. I had 240 volts total with 120 V in each leg both before and after the breaker with the breaker on, and no voltage after the breaker with it off. There was a switch in the circuit that would disconnect one leg to power off the motor. I did have phantom voltage present with the switch in the off position, but I assume that would disappear if I checked with a load present or with a low impedance meter, which I do not have. Since the switch only disconnected one leg, I removed the switch from the circuit for safety reasons and plan to replace it with a double pole switch to disconnect both energized legs when I turn the pump off.
So here are my questions: I assume that there must be a problem with my electrical supply, that manifests itself only under load. Either that or I just got extremely unlucky. Unlucky happens from time to time. What could possibly cause two motors to get smoked on the same circuit after mere seconds of operation? How can I test the circuit under load to discover any such problems? I've thought of using 100 W lightbulbs in series, so that they drop 120 V each on a 240 V circuit, but that would be a purely resistive load. What else should I test to ensure that when I install my next replacement motor that it doesn't get smoked as well?
Other information: The motor is on a 20 A 230 V GFCI circuit breaker made by Square D on a subpanel outside by the pool. The subpanel is on a 60 A 230 V breaker on the main panel in the house. As far as I know there are no junction boxes anywhere else in the circuit. I detected no shorts between the subpanel and the wire terminals that would connect to the motor.
Thanks, and sorry for the long post.
The new pump was a knock off, a 1.5 hp labeled White River. The sticker on it indicated that it came wired from the factory for 230 V operation, and I double checked per the schematic on the housing. I'm fairly certain that I wired it correctly. Ground to the ground screw, one leg to the line 1 terminal, and the other leg to the line 2 terminal. Upon energizing the motor, it turned very slowly and noisily and then tripped the breaker, within 3 seconds or so. I checked the rotor and found that it turned freely, so I reset the breaker and tried again. Once again, it turned slowly and noisily and tripped the breaker, this time with accompanying smoke, and again within 3 seconds or so.
I removed the pump and checked my supply voltage again. I checked both legs and the total voltage both before and after the breaker, both with the breaker on and off. I found everything to be correct, for no load at least. I had 240 volts total with 120 V in each leg both before and after the breaker with the breaker on, and no voltage after the breaker with it off. There was a switch in the circuit that would disconnect one leg to power off the motor. I did have phantom voltage present with the switch in the off position, but I assume that would disappear if I checked with a load present or with a low impedance meter, which I do not have. Since the switch only disconnected one leg, I removed the switch from the circuit for safety reasons and plan to replace it with a double pole switch to disconnect both energized legs when I turn the pump off.
So here are my questions: I assume that there must be a problem with my electrical supply, that manifests itself only under load. Either that or I just got extremely unlucky. Unlucky happens from time to time. What could possibly cause two motors to get smoked on the same circuit after mere seconds of operation? How can I test the circuit under load to discover any such problems? I've thought of using 100 W lightbulbs in series, so that they drop 120 V each on a 240 V circuit, but that would be a purely resistive load. What else should I test to ensure that when I install my next replacement motor that it doesn't get smoked as well?
Other information: The motor is on a 20 A 230 V GFCI circuit breaker made by Square D on a subpanel outside by the pool. The subpanel is on a 60 A 230 V breaker on the main panel in the house. As far as I know there are no junction boxes anywhere else in the circuit. I detected no shorts between the subpanel and the wire terminals that would connect to the motor.
Thanks, and sorry for the long post.
